Week 8 - Respiratory disease

Question 1

airways summary:

Answer 1

Sinuses: Cavities in the skull that help humidify and filter the air we breathe.
Pharynx: A passageway that connects the nose and mouth to the larynx and esophagus.
Larynx: Also known as the voice box, it facilitates airflow to the trachea and helps protect the airway.
Trachea: The windpipe that directs air into the lungs.
Bronchial Tubes: Branches from the trachea that carry air into each lung.
Lungs: Main organs of respiration where gas exchange occurs.
Bronchioles: Smaller branches of the bronchial tubes leading to the alveoli.
Alveoli: Tiny air sacs surrounded by capillaries where oxygen enters the blood, and carbon dioxide is removed.

Question 2

Gas exchange process

Answer 2

Alveolus and Alveolar Duct: Tiny air sacs where gas exchange takes place, connected by ducts.
Pulmonary Artery and Vein: The pulmonary artery carries oxygen-poor blood to the alveoli, while the pulmonary vein carries oxygen-rich blood away.
Capillaries: Surround the alveoli, allowing close contact between blood and air for gas exchange.
Red Blood Cells: Pick up oxygen (O₂) and release carbon dioxide (CO₂).
Alveolar Epithelium and Basement Membrane: Thin layers that facilitate diffusion of gases.
Surfactant: A substance that reduces surface tension in alveoli, preventing collapse and aiding gas exchange.
Alveolar Macrophages: Immune cells that clean debris to maintain alveolar health.
Oxygen diffuses from the alveolar air into the capillaries, binding to red blood cells, while carbon dioxide diffuses from the blood into the alveoli to be exhaled.

Question 3

Inspiration:

Answer 3

the process of breathing in to acquire oxygen
- Chest cavity changes size (diaphragm moves downwards and external intercostal muscles outwards), creating an increase in chest cavity size
- Pressure moves from high (in the environment) to low (in the lungs)
- Pressure is then lower in the lungs vs atmosphere
- Air pulled into the lungs

Question 4

Expiration

Answer 4

the process of removing carbon dioxide out of the body through the lungs
- Chest cavity decreases (diaphragm & external intercostal muscles relax)
- Intrathoracic pressure increases which pushes air out (higher than the atmospheric pressure)
- Air flows passively out of the atmosphere

Question 5

Measurement of ventilation:

Answer 5

Spirometry - nose clip on to ensure all gases are collected by the spirometer. Can also measure an overall trend in lung function

Tidal Volume (TV): The amount of air inhaled or exhaled during normal breathing (middle yellow zone). At rest ~500ml

Inspiratory Reserve Volume (IRV): The additional air that can be inhaled after a normal inhalation (top orange zone).

Expiratory Reserve Volume (ERV): The additional air that can be exhaled after a normal exhalation (green zone below TV).

Residual Volume (RV): The air remaining in the lungs after a maximal exhalation (bottom purple zone).

Inspiratory Capacity (IC): The maximum volume of air that can be inhaled (TV + IRV).

Functional Residual Capacity (FRC): The air left in the lungs after a normal exhalation (ERV + RV).

Vital Capacity (VC): The total amount of air that can be exhaled after a maximal inhalation (IRV + TV + ERV).

Total Lung Capacity (TLC): The total volume of air the lungs can hold (TV + IRV + ERV + RV).

Question 6

ventillation

Answer 6

movement of air in and out of the airways

Question 7

diffusion

Answer 7

exchange of o2 and co2 (via the capillaries into the bloodstream)

Question 8

Respiratory diseases causes:

Answer 8

• Lung inflation
• Obstruction
• Interstitial lung disease (problems with the spaces in the lungs)
• Pulmonary circulation
• Acute respiratory disorder (e.g., trauma- lung puncturing)

Anatomy, muscles involved (damaged or neural pathways dysfunction), lung structure, low haemoglobin levels

Question 9

Common respiratory diseases:

Answer 9

• Asthma
• COPD (umbrella term for chronic bronchitis, emphysema)
• Obstructive airway disorders – caused by disorders that limit expiratory airflow

Question 10

Asthma:

Answer 10

• Chronic disorder of the airways (can’t be cured)
• Causes episodes of airway obstruction, bronchial hyperresponsiveness (higher responsiveness of bronchioles which leads to airway inflammation)
• Generally caused by an Exaggerated hyperresponsiveness to stimuli e.g., grass cutting, dust
• Inflammatory cells damage bronchial epithelium
• Signs and symptoms: wheezing, chest tightness, immobilising asthma attack
• Spontaneous or in response to triggers, resp infections, emotional stress or weather changes
• Physical obstruction of air
• Asthma attack – exacerbation of the condition. Air gets trapped in the alveoli. Smooth muscle around airways tightens which further obstructs the airways. Take a breath in but can’t fully expire – lungs hyperinflate

Question 11

Exercise-induced asthma

Answer 11

• Only experience wheezing and bronchospasm during exercise
• Unknown cause
• Important factors: type of air (polluted, cold or warm), level of exercise (intensity), any other respiratory diseases

Question 12

Asthma prevalence:

Answer 12

• Worldwide: over 300million people, more than 10% of children aged 6-7years old. Incidence higher in children than adults
• UK: more than 8 million people (~12% population). Accounts for 2-3% of primary care consultations, 60,000 hospital admissions, and 200,000 bed days per year in the UK
• Occupational asthma may account for 9-15% of adult-onset asthma; reported to be the most common industrial lung disease in the developed world. E.g., exposed to asbestos

Question 13

Chronic obstructive pulmonary disease (COPD):

Answer 13

• Chronic and progressive
• Recurrent obstruction of airflow in pulmonary airways
• Umbrella terms: 1) emphysema (enlargement of airspaces and destruction of lung tissue) 2) chronic obstructive bronchitis (increased mucus production, obstruction of major and small airways, and a chronic productive cough, chest pains)
• As condition worsens, breathing requires more energy
• Symptoms: fatigue, cough, exercise intolerance, sputum production, shortness of breath, exacerbation, air hunger, gasping, external dyspnoea, increased effort to breath
• Primarily people in their 50-60s who are diagnosed with COPD
• Worsens as disease progresses
• > productive cough in AM
• Infections increase hyperinflation and gas trapping
• Leading cause of COPD = smoking
• Respiratory infections do not cause COPD – but can make people with COPD more unwell

Question 14

COPD prevalence

Answer 14

• Worldwide: 174million people, 3.2 million deaths due to COPD, 4th leading cause of death, ~90% of deaths in <70 years of age occur in LMIC
• UK: 3 million people impacted (2 million undiagnosed), 2nd lahest cause of emergency admission, 1.4million GP consultations per year

Question 15

Management of respiratory disease

Answer 15

• Smoking cessation
• Influenza vaccinations
• Oxygen therapy
• Medication e.g., inhalers
• Pulmonary rehabilitation

Question 16

Pulmonary rehab:

Answer 16

• 6-12 weeks
• Typically, twice a week, supervised (however covid accelerated the plans becoming more self-directed)
• Exercise (aerobic & resistance) + educational sessions
• Cochrane review (2015): found improvements in 4 QoL domains (dyspnoea, fatigue, emotional function and mastery (CRQ)) and improvement in functional and maximal exercise capacity
• No longer need trials comparing pulmonary and usual care – there is overwhelming research already to suggest pulmonary rehab works and is beneficial
• Common outcome measures for pulmonary rehab: QoL, mood state (anxiety and depression), breathlessness & fatigue, strength, exercise capacity (typically a 6min walking test)

Question 17

UK CMO Physical Activity Guidelines:

Answer 17

• Want to improve balance – reduce the chance of frailty and falls
• Minimise sedentary time
• Build strength
• Be active (at least 150min of moderate exercise a week or 75min vigorous)
• Some is good more is better

Question 18

COPD – cycle of (in)activity:

Answer 18

Patients with COPD sat at home resting – leads to decreased strength (atrophy) – weaker muscles (less efficient/ use more o2) – symptoms get more severe when doing daily activities – patients don’t want to feel breathless, so they start to do less activity – activity further declines – cycle continues.
Patients with COPD are active – muscles become stronger – they use less o2 – become less breathless in daily task - feel better and do more – cycle continues

Question 19

Relationship between respiratory disease and PA:

Answer 19

• *Gold stage 1 is the least severe, gold stage 4 is the worst
• PA is reduced in COPD patients from Gold stage II
• Those with COPD who perform some level of regular PA have a lower risk of both COPD admissions and mortality
• COPD was more prevalent in males – more males smoked
• 20 year follow up study, N = 2386 ppts with COPD
• PA ~ walking or cycling 2 hours/week or more was associated with a 30-40% decrease in the risk of COPD hospital admission and respiratory mortality
• The more severe someone’s COPD was, the fewer the steps they did

Question 20

Asthma and PA:

Answer 20

• Systematic review – 20 studies
• “Found mixed results of the effects of physical activity on asthma outcomes were found. Most studies suggest that physical activity improves asthma control, quality of life, lung function parameters, and inflammatory serologies, while three found no improvements in any of these outcomes. No studies reported worsening asthma outcomes.”